Human posture simulation to assess cumulative spinal load due to manual lifting. Part II: accuracy and precision

For assessing a large number of variable manual lifting jobs, posture specification for using the University of Michigan Three Dimensional Static Strength Prediction Program and the revised National Institute for Occupational Safety and Health Lifting Equation may be time-consuming, tedious and subject to human errors. To expedite data analysis with desirable accuracy and precision for the two risk assessment tools, a new data analysis method based on human posture simulation was developed and evaluated. The accuracy and precision of the posture simulation method were evaluated by a repeated measures study design with six postures, three viewing angles and three trial repetitions as experimental factors. The effects of the experimental factors on the average accuracy and precision of the simulation method are reported and discussed. The study results also demonstrated pros and cons of human posture simulation as a means of posture specification for ergonomic risk assessments. The findings about the accuracy and precision of the human posture simulation method for quantifying the risk of musculoskeletal disorders due to manual materials handling may provide researchers with a new way of ergonomic assessments.     

Cumulative spinal loading exposure methods for manual material handling tasks. Part 2: methodological issues and applicability for use in epidemiological studies

Objective: The goal of this paper is to review and discuss methodological issues related to cumulative spinal loading exposure assessment methods. Background: Research has indicated that there likely is an association between integrated spinal loading and lower back pain. A number of studies have been conducted to evaluate cumulative load; however, comparisons between studies is difficult due to the use of different methods for the assessment of cumulative spinal loading. Methods: A comprehensive electronic search was conducted to locate articles dealing with methods of cumulative spinal loading estimation. The articles were evaluated with respect to methods for obtaining postural data, methods for estimating spinal loads, methods for integrating loads over time and spinal load parameters to be measured. Results: Thirteen articles were located. A summary of the methods used to estimate cumulative spinal load is described and evaluated. Conclusions: There is a pressing need for integrated spinal loading methods that are reliable, valid and practical for use in large occupational epidemiological studies. A number of research needs were outlined aimed at improving the ability to use cumulative load to predict risk of low back disorders due to manual material handling.